1. Field of the Invention
The present invention relates to a capsule-type medical apparatus, comprising a capsule body which is inserted in a living body to perform observation or the like and an external apparatus, and a communication method for the capsule-type medical apparatus.
2. Description of the Related Art
The latest medical apparatuses include conventional capsule-type medical apparatuses made so as to attain living-body information by having the patient swallow a capsule and to send that living-body information to an external apparatus.
Of these, the U.S. Pat. No. 5,604,531 proposes an in vivo video camera system wherein an image pickup element is placed in a living body and sends the captured images of the digestive tract to outside of the living body. Also, Japanese Patent Laid-open Publication No. H02-31738 discloses a medical capsule constituted to execute prescribed functions inside the living body according to commands from an external apparatus. This medical capsule provides means for identifying each of the capsules when a single patient swallows a plurality of capsules. Also, it is shown that the medical capsules can be used even in the case where a plurality of patients in a single room have each a swallowed capsule.
In the capsule-type medical apparatus, the capsule and the external apparatus for receiving and accumulating data from the capsule are paired once, and then that pairing must be maintained until the examination is ended. In this capsule-type medical apparatus, it is necessary to make a connection with the original partner in the case where the communication connection between the capsule and external apparatus is broken for any reason (a situation wherein the external apparatus must be separated from the living body during the examination). In this case, a connection must not be made with a capsule swallowed by another neighboring person.
With a wireless modem using the 429 MHz band, for example, instead of a capsule-type medical apparatus, the wireless instruments are provided with a switch for setting its own identifier that is constituted so that communicating partners are identified each other.
By the way, when the data sent from the capsule are image data, it is not necessarily the case that images of all internal organs are to be captured after the capsule is swallowed. When the capsule contains a battery, it is desirable to photograph and perform wireless sending of the photographed image signal only when the capsule arrives at the internal organ that is the destination. Also, it is necessary to alter the photographing interval according to the speed of movement of the capsule.
Sending control commands from the external apparatus to the capsule to control the capsule from outside the living body has been considered as means therefor, but it would be necessary to control each specific capsule and to set the identifier for each capsule. However, when considering the application of the abovementioned wireless modem to a capsule-type medical apparatus, it is substantially impossible to establish a switch for setting the identifier in the capsule because of size limitations and the necessity for ensuring that the capsule be watertight.
Another idea considered was writing the abovementioned identifier to non-volatile electronic memory at the time when the capsule is produced. However, in the case where the capsules are shipped in large quantities, the number of digits of the identifier becomes too great. When the number of digits of the identifier becomes too great in this way, the transmission efficiency will drop because the identifier must be placed in the packet header for each packet. Furthermore, a large amount of power will be consumed in the transmission of the identifier portion on the capsule side. Improvements are desired in view of the lifespan of the small battery placed within the capsule.